Ana Gimenez-Garcia, Tomer Shenar, J. M. Torrejon, Lidia M. Oskinova, S. Martinez-Nunez, Wolf-Rainer Hamann, J. J. Rodes-Roca, A. González-Galan, J. Alonso-Santiago, C. González-Fernández, Guillermo Bernabeu, Andreas Alexander Christoph Sander
- Aims. To close this gap, we perform a comparative analysis of the optical companion in two important systems: IGR J175442619 (SFXT) and Vela X-1 (SGXB). We analyze the spectra of each star in detail and derive their stellar and wind properties. As a next step, we compare the wind parameters, giving us an excellent chance of recognizing key differences between donor winds in SFXTs and SGXBs. Methods. We use archival infrared, optical and ultraviolet observations, and analyze them with the non-local thermodynamic equilibrium (NLTE) Potsdam Wolf-Rayet model atmosphere code. We derive the physical properties of the stars and their stellar winds, accounting for the influence of X-rays on the stellar winds. Results. We find that the stellar parameters derived from the analysis generally agree well with the spectral types of the two donors: O9I (IGR J17544-2619) and B0.5Iae (Vela X-1). The distance to the sources have been revised and also agree well with the estimations already available in the literature. In IGR J17544-2619 we are able toAims. To close this gap, we perform a comparative analysis of the optical companion in two important systems: IGR J175442619 (SFXT) and Vela X-1 (SGXB). We analyze the spectra of each star in detail and derive their stellar and wind properties. As a next step, we compare the wind parameters, giving us an excellent chance of recognizing key differences between donor winds in SFXTs and SGXBs. Methods. We use archival infrared, optical and ultraviolet observations, and analyze them with the non-local thermodynamic equilibrium (NLTE) Potsdam Wolf-Rayet model atmosphere code. We derive the physical properties of the stars and their stellar winds, accounting for the influence of X-rays on the stellar winds. Results. We find that the stellar parameters derived from the analysis generally agree well with the spectral types of the two donors: O9I (IGR J17544-2619) and B0.5Iae (Vela X-1). The distance to the sources have been revised and also agree well with the estimations already available in the literature. In IGR J17544-2619 we are able to narrow the uncertainty to d = 3.0 +/- 0.2 kpc. From the stellar radius of the donor and its X-ray behavior, the eccentricity of IGR J17544-2619 is constrained to e < 0.25. The derived chemical abundances point to certain mixing during the lifetime of the donors. An important difference between the stellar winds of the two stars is their terminal velocities (v(infinity) = 1500 km s(-1) in IGR J17544-2619 and v(infinity) = 700 km s(-1) in Vela X-1), which have important consequences on the X-ray luminosity of these sources. Conclusions. The donors of IGR J17544-2619 and Vela X-1 have similar spectral types as well as similar parameters that physically characterize them and their spectra. In addition, the orbital parameters of the systems are similar too, with a nearly circular orbit and short orbital period. However, they show moderate differences in their stellar wind velocity and the spin period of their neutron star which has a strong impact on the X-ray luminosity of the sources. This specific combination of wind speed and pulsar spin favors an accretion regime with a persistently high luminosity in Vela X-1, while it favors an inhibiting accretion mechanism in IGR J17544-2619. Our study demonstrates that the relative wind velocity is critical in class determination for the HMXBs hosting a supergiant donor, given that it may shift the accretion mechanism from direct accretion to propeller regimes when combined with other parameters.…
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MetadatenVerfasserangaben: | Ana Gimenez-Garcia, Tomer ShenarORCiDGND, J. M. Torrejon, Lidia M. OskinovaORCiDGND, S. Martinez-Nunez, Wolf-Rainer HamannORCiDGND, J. J. Rodes-Roca, A. González-Galan, J. Alonso-Santiago, C. González-Fernández, Guillermo Bernabeu, Andreas Alexander Christoph SanderORCiDGND |
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DOI: | https://doi.org/10.1051/0004-6361/201527551 |
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ISSN: | 1432-0746 |
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Titel des übergeordneten Werks (Englisch): | Siberian Mathematical Journal |
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Verlag: | EDP Sciences |
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Verlagsort: | Les Ulis |
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Publikationstyp: | Wissenschaftlicher Artikel |
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Sprache: | Englisch |
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Jahr der Erstveröffentlichung: | 2016 |
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Erscheinungsjahr: | 2016 |
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Datum der Freischaltung: | 22.03.2020 |
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Freies Schlagwort / Tag: | X-rays: binaries; accretion, accretion disks; methods: observational; stars: atmospheres; stars: winds, outflows; techniques: spectroscopic |
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Band: | 591 |
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Seitenanzahl: | 25 |
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Fördernde Institution: | Spanish MICINN under FPI Fellowship [BES-2011-050874, AYA2010-15431]; Leibniz Graduate School for Quantitative Spectroscopy in Astrophysics; Leibniz Institute for Astrophysics Potsdam (AIP); Institute of Physics and Astronomy of the University of Potsdam; Spanish Ministry of Economy and Competitiveness [ESP2013-48637-C2-2P, ESP2014-53672-C3-3-P]; Spanish unemployment agency; Deutsche Forschungsgemeinschaft (DFG) [HA 1455/26]; NASA [NAS5-26555]; NASA office of space science [NAG5-7584]; National Aeronautics and Space Administration; National Science Foundation |
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Organisationseinheiten: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Physik und Astronomie |
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Peer Review: | Referiert |
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